4 ms·

Interesting that it passes/returns structs by value quite a lot which is not usual in C (in my experience.) I assume there's a reason for this? e.g. static Her

• jeffreyrogers 9y ago
  I think it's just for simplicity, since all that copying can't be faster than passing in a reference to it.
  • munificent 9y ago
    You might be surprised. For small structs, copying is very fast and may give you a result with better locality. Passing around structs by pointer means more pointer dereferencing, which has its own overhead and can cause cache misses. Performance of modern CPUs is very nonobvious.
    • glouwbug 9y ago
      You are correct. On a much larger project with a similar software engine, if I change all structs I pass by value to pass by reference my instruction count shoots up by 40% according to cachegrind (flto + ofast). Amazing how powerful pass by value can be when it comes to pod structs.
• glouwbug 9y ago
  I do so to enforce a single return value from functions. Given: static void damage(const Hero* hero, const Sprite* sprite); The const can easily dropped later in production from both entities, potentionally creating two return values. This is analougous to good use of privacy in C++ classes. hero = spin(hero, key); Becomes: hero.spin(key); Where external objects dictate the private state of the hero object. Pointer aliasing is another thing. Inlining is easier with fewer pointers. A fun C++ experiment is to count your instruction and data cache points with valgrind's cachegrind with pod types both passed by value and by reference (&).